I was taught that hollandaise sauce was only safe to serve within 3 hours of making it, then it must be thrown out. I guess this was always the magic of a true hollandaise, a fleeting, brief challenge that was worth the effort every time.

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Many years ago I was taught "the" way to make Hollandaise which it turns out, like many cooking "truths", not the best method. The classic method can create a hazardous situation and thus the extremely short life (today we'd say 2 hours max. then toss). Ditto for blender methods.

I've been bringing the yolks up to 160F for so long I forgot not everyone does things the safe way. In the U.S., there's a 1 in 20,000 chance that an egg is contaminated with pathogenic bacteria. Not a large risk but there's really no reason not to make a safe Hollandaise. By whisking the acid with the yolks before heating, they won't curdle before pasteurization is achieved. The finished sauce can be held at 160 for as long as necessary.

Good information, Chef Ono and Slow Cooked. I should have said that the recipe I used is a "mock hollandaise," an acceptable, durable and quick hollandaise. I do appreciate the more delectable classic sauce--Chef Ono, would you share your recipe?